Maybe you have a valid argument. But Brahmanism can be considered a religion, can it not?
From everything I have read in original sanskrit - NO.
Short version: a religion is a set of beliefs, gods, rituals, and social practices (or a subset of these). brahmin (there is no ism possible) are to seek everything - beliefs, gods, rituals and practices. thus each brahmin is a prophet. can a religion handle each member being a prophet? when I say seek, it also includes accept and reject.
Longer version: All translations whether Sastry or Maxuller have suffered from one of two gaps - Sastry ofcourse had internalized the concepts by Brahminic training but couldn't find the accurate english words. Maxmueller was equipped with many more target words but couldn't get the underlying concepts, lacking brahminic training. He himslef would indirectly acknowledge this in his Sanhita in English (1869, still available in Princeton library). by citing at least three different interpretations for each Rg verse, he himslef playing the role of an arbiter. He would torture himself trying to which of the three is most correct but he was aware that he was applying that subset of tools he had learnt.
As a result people going by one school end up thinking of Rg as prayers to the elements; others contemplate it as precursor to rituals (found in the other vedas); some of the philosophically inclined prefer to see it as repositary of certain cardinal mantras .....and so on.
But the fundamental issue is when rules of conjunction and a meanings associated at moment level and below, it is easy to misinterpret even for sanskrit scholars who know the grammar but not the domain concept - an elephant, a star and a water body from the same two syllables !
this is why (imo) Vedas were only handed over orally with set sounds and meters and taught only through a guru. Books and palm leaves couldn't cut it. May be now that we have video it may become a bit better but the depth and breadth of concepts is so vast , we may have to for now conclude brahminic training is only possible under gurukul methods
I mean what do you do for example in this case : there are vedic "phrases" (phrase is my approximation in english for that language structure) which even a person knowing sanskrit cannot read/say properly unless he has had the correct correct breadthing technique ! and how do you explain to new language students that certain meanings will change based on how fast you recurse certain "verses" !! These require 18 / 20 years of training under a guru paying personal attention to your voice, breadth, lisps....
Anyway let us stop at this.